In a manufacturing process of a semiconductor device, various devices with a trench isolation have been developed. For example, as a MOSFET having high-voltage resistance, a MOSFET having a trench gate structure has been developed. Also, in the manufacturing process of an imaging device such as a CMOS sensor or a CCD sensor, the trenches are formed between the adjacent light receiving elements so as to prevent generation of crosstalk between the pixels. The depth of the trench influences the performance of the device and the yield rate of the production of the devices. For instance, in the production of the CMOS sensor, if the imperfect trench is formed, the leakage of the electric charges between the adjacent pixels may be increased, and the problem arises that the image quality is decreased.
A flash memory device with a laminate structure of memory elements has been developed. In the manufacturing process of the flash memory of the laminate type, a semiconductor layer and a silicon oxide layer are alternatively formed so as to form a multilayer structure. Then, in order to form a columnar transistor structure, a hole is formed in the multilayer structure and then a semiconductor material is embedded into the hole. In such manufacturing process of the flash memory device of the laminate type, if the hole to be formed in the multilayered structure is defective in structure owing to an etching process or if a foreign substance exists on the inner surface of the hole, the defective columnar transistor is formed and also the yield rate of the flash memory device is decreased. Therefore, the development of the microscope and inspection apparatus which can check whether the semiconductor layers are formed exactly or not and whether the various holes or grooves are correctly formed in the manufacturing step of the various semiconductor devices is strongly demanded. Furthermore, the development of the inspection apparatus which can detect the defective area existing in the multilayer structure including the hole and the groove from outside of the semiconductor body is strongly demanded.
In the manufacturing process of the semiconductor device, it has been known to observe or inspect the semiconductor substrate using the dark-field microscope (for example, see PLT 1). In this known dark-field microscope, since the sample surface is illuminated by use of an illumination beam having ring shape, the objective lens is arranged to form a dual structure, and an optical path of imaging optical system including the objective lens system is formed in the inside space and an optical path in which the illumination beam propagates is formed outside of the optical path of the objective lens system. The scattered light emanating from the sample surface is collected by the objective lens.
Further, a microscope in which the sample surface is illuminated by illumination beams having different wavelengths each other is also known (for example, see PLT 2). In this known microscope, a plurality of light sources for producing the illumination beams having different wavelengths are arranged outside of the optical path of the imaging optical system, and the illumination beams of different wavelengths are projected toward the illumination area including the optical axis of the objective lens. The wavelengths of the illumination beams are infrared region and visible region.
PLT 1: Japanese Patent Publication (A) No. 2006-178199
PLT 2: Japanese Patent Publication (A) No. 2010-257585